Script files(.fsx) not working

### Description

No completion, type signature on F# script files(.fsx).
Code files(.fs) works as expected.

### Repro steps

1. Step A

open a simple script file, Foo.fsx:
```fsharp
let x = 10
x.ToString()
x.T
```

2. Step B
- M-x eglot
- highlight x, ToString
- try complete x.T

### Expected behavior

- x, ToString type signatures should show on mini-buffer
- x.T should display completions

### Actual behavior

"flymake:Wait" on mode line never goes away.

And Error:
```lisp
[...]
client-request (id:28) Sat Dec 7 16:17:15 2019:
(:jsonrpc "2.0" :id 28 :method "textDocument/completion" :params
(:textDocument
(:uri "file:///home/me/Test/fsharp/core-3.0.101/hello-world/Foo.fsx")
:position
(:line 5 :character 3)
:context
(:triggerKind 1)))

server-reply (id:28) ERROR Sat Dec 7 16:17:15 2019:
(:jsonrpc "2.0" :id 28 :error
(:code -32603 :message "no type check results"))

internal (id:24) Sat Dec 7 16:17:25 2019:
(:timed-out :textDocument/signatureHelp :id 24 :params
(:textDocument
(:uri "file:///home/me/Test/fsharp/core-3.0.101/hello-world/Foo.fsx")
:position
(:line 5 :character 3)))
```

### Known workarounds

Stick with .fs and never touch .fsx? :(

### Related information

* Operating system
Ubuntu 19.10
* Branch
melpa version fsharp-mode-20191130.1857
* Emacs version
GNU Emacs 26.3
* .NET Runtime, CoreCLR or Mono Version
.net core 3.0.101